Bug bores into oaks

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A new threat to Ramona has arrived in the form of an insect smaller than a penny. The Goldspotted Oak Borer (GSOB) that has been felling trees at an alarming rate in Descanso has reached the outskirts of south and west Ramona.

“This is an Armageddon of sorts for the trees,” said Martin Aguilera, risk assessment officer for the Resource Conservation District. “GSOB has the potential to eradicate California oak trees throughout California.”

The pest has been aggressively attacking three oak species, boring into the wood and killing more than 20,000 backcountry oaks. The U.S. Forest Service has been following leads on GSOB popping up in backyards and parks, and migrating from dormant woodpiles.

The dead and dying trees have the potential to become fuel for the next wildfire.

“From the larva stage to a dead tree seems to take approximately five years,” said Aguilera during a recent visit to Ramona. “During that time, GSOB might be breeding and migrating to other trees as well. The damage potential has already proven to be huge.”

Fires aren’t the only worry. Lower property values are a possible result as well. In an already depressed housing economy further hits to a property can only exacerbate the problem, said Aguilera.

“I moved to Julian because I want to live in a forest,” he said. “Forests have trees, and our trees are in trouble.”

Aguilera met members of the Ramona West End Fire Safe Council in Ramona recently.

According to the forest service, the mortality rates of infected trees range from 65 percent to 100 percent. Authorities are unsure why the beetle targets one tree and not another, but it is being investigated by entomologists and scientists through various coordinating agencies in the forest service and University of California system. Agencies are taking the time to do indepth studies for appropriate solutions. In the meantime, the bug still flies.

The spread of the beetle is anticipated for several reasons. First, it can fly an estimated five miles a day. That leaves a lot of trees as possible targets. Of the more than a dozen species of oaks, the GSOB seems to be targeting California black oaks, canyon live oaks and coast live oaks.

Infested firewood

The spottiness of infection, said Aguilera, suggests some of the spreading damage may be the result of moving firewood from one part of the county to another. If the infestation were purely pest-propelled, there should not be areas of healthy trees between areas of devastation, he said.

“If people just make different choices for wood, the pest might be kept out of certain areas,” Aguilera said. “A lot of people go to wood lots and choose oak because of how hot it burns. Choose eucalyptus instead. Orange wood is another wood not affected by the beetle. If there isn’t a demand for oak in an area, then the wood suppliers will stop bringing it in.”

Because oak trees are not considered to be an agricultural product, movement on quarantine is depressingly slow, said Aguilera. Agriculture is not affected, so quarantine is not warranted by the agencies that would implement it, he explained.

“Though native peoples use the acorns for food as an important part of their culture, this is not a (mainstream) food crop we are talking about here,” he said.

There are countless running trails and parks with thousands of oak trees. If the trees keep dying, the trails will not have the shade once provided and the parks would lack the ambiance of trees that grow for many generations, said Aguilera.

The aesthetics of the oaks are not the only loss. As trees die, the towering mass becomes an unstable threat, according to the forest service. Trees falling on people then become a hazard, a tragedy avoidable only by park closure, according to the forest service. Nearly $500,000 has been spent and lost through either the removal of dead trees or park closures in Southern California since the pest became a natural force to be reckoned with, reports the forest service.

Rangers at Dos Picos County Park in Ramona have taken steps to protect the park’s more than 350 oaks. Campers are not allowed to bring in oak firewood, and rangers say the pest has not yet made way into the park.

Other parks, such as William Heise County Park in Julian, are already facing the problem.

According to the forest service, GSOB appears to have come from Mexico or Guatemala before moving to Arizona and California. First detected in Arizona in 2006, the pest was held in check by the desert heat.

As desert trees died, people cut them down, and some sold the firewood near campgrounds, said Aguilera.

“Infested firewood appears to be a major factor to contend with in the control of this little bug that will decimate a large number of trees in California,” said Aquilera.

Some homeowners in Descanso have lost every tree on their property, said Aguilera.

“These trees are 3 to 4 feet across—huge trees taken down by this tiny bug,” he said. We have been marking trees and anticipating their removal in July with agreements from owners. We take them out for free, but we only leave one cord of wood behind that is then encapsulated in plastic for a year so GSOB cannot get out —thermal annihilation.”

Many homeowners are reluctant to give up the wood.

“They want to keep it to burn it or give it to friends or to sell it,” said Aguilera. “We need to help them understand the utter devastation this pest creates when it gets out of the wood and moves on to another area.”

Treating trees

GSOB is similar to the ash-borers that have devastated forests in the West, he said. Systemic treatment of trees on properties is possible, but expensive, and there is no proof that it actually works—no scientific substantiation.

“It will take 5 to 10 years for new insecticide that will work on GSOB specifically,” said Aguilera.

Oaks are being treated with the same injections and sprays by arborists, but this is something still being studied and in no way a long-term solution. The effectiveness of injections wears off, sprays wear off, and the bug can come back from another tree.

A final solution to the eradication of GSOB in California’s oak species is expected to be long coming. In the meantime, Aguilera suggests that volunteers begin their own research of sorts.

“Search out the non-impacted species...to see what survives better with less care in our climate,” he said.

Immume species

Engelmann oaks seem to be a species the borer is not interested in. Ramona is lucky in its elevation, because “a variety of non-native shade trees can be planted here that will survive in Ramona,” said Aguilera. “Planting non-native/non oak species that won’t be taken out by the bug is crucial to the long term success of revegetation to areas susceptible to GSOB.”

Buy orange wood, eucalyptus and other species already in the area, said Aguilera.

“Don’t buy oak,” he said. “That way you haven’t moved any wood that might have GSOB in it. Don’t share wood from an oak on your property that has been cut down. Get in touch with the groups who are working to combat this.”

Aguilera suggests contacing the University of California or him.

“We have people who can help with identifying infested trees as well as solutions to their removal,” said Aguilera. “Experienced volunteers will be able to completely encapsulate felled oaks in plastic. Simply covering it with a tarp just won’t do it. We need to neutralize possible infestations spreading.

“We can take precautions and do revegetation. I see it as passing a legacy my grandchildren can enjoy 50 years from now.”

The forest service has an information booth at the San Diego County Fair in Del Mar.

“We are going to have a huge round slice of a tree that came from an infested tree,” said Aguilera. “It is polyurethaned in order to show the public the path GSOB takes into the heart of the tree.”

According to UC Riverside Center for Invasive Species, GSOB’s damage is not confined to the oak trees themselves. Oak trees are vital to foothill eco-systems. Certain animals rely entirely on the oaks for shelter and food.

Preventing spread

To help prevent the spread of GSOB, the UC Riverside Center for Invasive Species offers the following tips for helping keep goldspotted oak borer from spreading:

•Do not transport oak firewood into or out of campgrounds or parks;

•Chip infested oak wood to 1-inch pieces;

•Cover stored oak firewood with 6mm, UV-stabilized, durable plastic tarps in the spring. Secure all the edges of the tarp to the ground to prevent beetles from escaping;

•Season oak firewood. Remove the bark and place the wood in direct sunlight.

For more information about GSOB, visit groups.ucanr.org/GSOB/.

The Master Gardener’s Association may be contacted for assistance with plant selection and planting tips: mastergardenerssandiego.org.

To identify and get help for infested trees, contact Aguilera at 619-749-4232 or by e-mail at martin.aguilera@rcdsandiego.org.

The Ramona West End Fire Safe Council has scheduled a GSOB presentation at the pavilion in Dos Picos County Park on Thursday, July 8, at 7 p.m. The public is encouraged to attend.

More information about the West End Fire Safe Council meeting is available from Kristi Mansolf at 760-445-8545 or kmansolf@gmail.com.